Core and process of forming the same



latented Mar. 25, 1930 UNITED STATES EMIL L. LEASMAN, OF MILWAUKEE, WISCONSIN com: AND PROCESS or rormme T m smn No Drawing. Application filed June 20, 1927, Serial No. 200,283. Renewed, June 27, i929.

Themethod of forming cores-now in general use has. many disadvantages among a which is that the cores after being formed must be baked at excessive temperatures to harden the same and as the binder used therein often contains organic matter, the baking 0d of forming cores is that baking the cores at the necessary high temperature and the consequent, burnmg of the orangic matter contained therein by the hot metal of the castings causes carbonaceous deposits about the grains of ."sand and, therefore, renders the sand worthless for future use.

Another objection to the cores of the present type is that it is extremely difiicu'lt to remove the same from the castings, the usual .20 method of chipping and rapping requiring considerable time and frequently cracking the castings when the walls are thin.

With thev above and other objections in mind, this invention has as one of its objects 2 a process of forming cores which does not require baking at excessive temperatures and which when completed forms a strong, durable core. v 'Another. object Tofthis invention resides in an. improved process of formingcores and the like which contain a binder of a nonorangic nature so that the hot moltenmetal striking the cores has no injurious effect upon I' the sand and prevents the formation of car-v bon deposits. p

v A further object of this invention resides in an improved process of making cores which 7 produces cores of a hard and durable nature,

but capable of being readily disintegrated by wetting so that their removal from castings 'is a comparatively simple matter.

And a still further object of this invention resides in the provision of a binder for cores and thejlike which consists of'sodium phosphates which act on the natural clay 1 contained in the sand to accomplish a temporary set or hardening thereof.

. The above objects are obtained. by'the use of a binder consisting of one or all of the following sodiumphosphates:

p 1. Tertiary or tri-sodium phosphate, which has the chemical formula of Na PO .12H O.

. which has the chemical formula of v Na HPO4-12H2O.

3. Primary or mono-sodium which hasthe chemical formula 0 N aH PO H o.

causing the natural clay content of either core or molding sand to temporarily set or phosphate, 7 4

2. Secondary or normal sodium phosphate, I

Sodium phosphate has a characteristic of 1 harden when allowed to dry, therefore, the

forming of cores with this element as a binder 1s extremely simple and comparatively lnexpensive. In practice thesand is thoroughly mixed with the sodium phosphate and is then allowed to dry or if quicker hardening is desired, baked at a temperature as low asthat of boiling water (212 F.)

This relatively low baking temperature produces a considerable saving in fuel consum tion, and as no organic matter is used in the inder, it is impossible to burn the cores, as is very often the case in present foundry practice. Furthermore as the binder is formed ofinorganic matter there is nothing to decompose or char, and smoke or fumes heretofore common in core rooms isentirely eliminated, cores made with phosphate binders baking with a total absence of smoke of any kind. 5

The useof sodium phosphates as a binder further allows all of the sand forming the coreto be reclaimed, by merely adding the required'amount of new phosphate and water to bring it back to its original state. i

The phosphate binder maybe supplied in the solid state for use with wetsands or it may :be supplied ,in'aqueous solution to be i to wet the" core to remove it from a casting.

What I claim as my invention is: 1. The hereindesc'ribed process of forming a core, which consists in mixing a sand hay ing a clay content with sodium phosphate in forming the core, and in drying the core.

2. The hereindescribed process of forming a. core, which consists in mixing a sand hav ing a (31:1 content with sodium phosphate sus nde in water, in forming the core, and in ying the core. .7

3. A binder for use in making cores of sand havin a natural clay content, which consists of so ium phosphate havin the character? istic of acting on the naturafelay content of the sand to produce a temporary set.

4. A core formed of sand having a',c1ay

content, and sodium phosphate as the sole binding agent. In testimony whereof I hereimto afiix my signature.

EMIL L. LEASMAN. 

